CrMoW转子钢高温超高周裂纹扩展及疲劳行为研究  

On the Crack Propagation and Very High-Cycle Fatigue Behavior of CrMoW Rotor Steel at Elevated Temperature

作　　者：谢少雄[1] 李久楷[2] 侯方[2] 刘永杰[2] 王清远[1,2] 

机构地区：[1]四川大学空天科学与工程学院,成都610065 [2]四川大学建筑与环境学院,成都610065

出　　处：《实验力学》2016年第1期1-8,共8页Journal of Experimental Mechanics

基　　金：国家自然科学基金(11327801;11172188;11302142;11502151)

摘　　要：本文研究了超超临界汽轮机CrMoW转子钢在常温与600℃条件下的超高周旋转弯曲疲劳行为。实验中利用位移传感器原位监测试件挠度变化,研究裂纹的萌生与扩展特性。研究结果发现,在常温下,疲劳裂纹主要萌生于试样表面,但也发现超高周次疲劳破坏的裂纹萌生于内部的情形。600℃时,S-N曲线呈现直线下降的趋势;大多试样裂纹萌生区和初始扩展区发现非金属夹杂物,其裂纹萌生是表面裂纹起源和亚表面夹杂物相耦合的结果。裂纹萌生寿命占整个疲劳寿命的90%以上,裂纹萌生寿命百分比(Ni/Nf)随疲劳寿命的延长而增大,并且温度对裂纹萌生寿命百分比没有影响。The very high cycle rotate bending fatigue behavior of CrMoW rotor steel used in utralsupercritical steam turbine was studied at room temperature and 600℃ respectively.In experiment,the deflection change of specimen was in-situ monitored by displacement transducers,and the crack initiation and propagation were studied.Experimental results show that at room temperature,fatigue fractures mainly initiate on specimen surface,but interior crack initiation was also observed in ultra high cycle fatigue fracture;at 600℃,S-N curve presents a continuously downward trend.Inclusion was observed in crack initiation area and crack initial propagation area for most specimens.Crack initiation of these specimens is due to the coupling of surface crack source and inclusion in subsurface.Crack initiation life accounted for more than 90% of whole fatigue life.Crack initiation life percentage（Ni/Nf）increases with the increase of fatigue life.It was also found that temperature has no effect on crack initiation life percentage.

关 键 词：铬钼钨(CrMoW)转子钢 高温超高周疲劳 夹杂物 疲劳裂纹扩展 

分 类 号：TG142.1[一般工业技术—材料科学与工程]